Play this if you love insanely large hordes of high-HP, high-speed, mega-damage, infintely-respawning pale hairless zombies. Oh, also fighting them (and super-rapey gonome freak things) in near dark. Plus millions of respawning headcrab-bug creatures as well. And super-grunts…
Add to this the joy of fighting various insta-kill hordes with several tricky, obscure object hunts, and this map pair is really something… 'special'.

Otherwise, (if you are sane) stay clear!

It was very hard work for 2 players, would suit 10 better - coop is essential for survival. Transitions were jarring and weird, and the ending was very sudden.